Since copper and a copper alloy material are small in an electric resistance, and are excellent in electrical conductivity, they are expected in development on electric and electronic materials, and parts such as a connector, and a contact spring of mobile phones and various electronic instruments which are rapidly technically innovated continuously, and a beryllium copper alloy wire rod (e.g. JIS-H3270) has been conventionally used frequently.
However, since the beryllium copper alloy contains harmful beryllium in a composition thereof, and there is an environmental problem when this is recycled, use thereof has been being limited in recent years, and in the light of such the circumstances, the present applicant provided a copper silver alloy wire having both high strength property and electrical conductivity property due to the combined effect of a eutectic phase of Cu and Ag and Ni2Si particles, by inclusion Ag: 5.0 to 16.0%, Ni: 1.0 to 5.0%, and Si: 0.2 to 1.2% (see Patent Literature 1).
On the other hand, Patent Literature 2 discloses a copper alloy containing Ni: 1.5 to 4 mass %, Si: 0.30 to 1.2 mass % and a total of 0.03 to 0.5 mass % of one or two of Mn and Mg, with the remainder being composed of Cu and incidental impurities, in which a mass concentration ratio of Ni and Si (Ni/Si ratio) in the alloy composition is in a range of 4≦{Ni/Si}≦5, and discloses a Cu—Ni—Si copper alloy for electronic materials, in which, among the copper alloy, a size of an intercalator is 5 μm or less, a total of Ni, Si and oxygen concentrations in the intercalator is 10 mass % or more, and a ratio of the number of intercalators having a size of 1 μm or more and the total number of intercalators having a size of 0.1 μm or more is 0.1 or less.    Patent Literature 1: JP-A-2006-291271    Patent Literature 2: JP-A-2006-283107